Thioketones and process for preparing the same



Patented Sept. 13, 1949 THIOKETONES AND PROCESS FOR PREPARING THE SAME Robert H. Sprague, Rochester, N. Y.', assignor to Eastman Kodak Company, Rochester; N. Y., a corporation of New Jersey No Drawing.

Application February 24, 1947,

I Serial No. 730,564

- 12 Claims.

. p 1 :1 This invention relates to thioketones, to anhydro-meso-substituted carbocyanine hydroxides and to a process for preparing them. This invention also relates to alkylmercapto compounds prepared from the said thioketones.

I have found that thioketones and anhydromeso-substituted carbocyanine hydroxides are simultane'ously formed when a cyclammonium carboxyalkyl quaternary salt containing a reactive alkyl group is condensed withan ester of a dithiocarboxylic acid. The thioketones are new compounds as are the alkylmercapto compounds obtained therefrom by treatment with alkyl salts.

It is, accordingly, an object of my invention to provide new thioketones, alkylmercapto compounds and anhydro-meso-substituted carbocyanine hydroxides. A further object is to provide a process for the simultaneous preparation of these compounds. Other objects will become apparent hereinafter. ,7

In accordance with my invention, I condense a cyclammonium carboxyalkyl quaternary salt selected from those represented by the following general formula: 6 v V R-1 1 lc-omin wherein R represents a carboxyalkyl group, e. g. carboxymethyl, ,B-carboxyethyl, c-carboxyethyl, 'y-carboxypropyl, 0c, Y-dicarboxypropyl, etc., X represents an anion, e. g. chloride, bromide, iodide, perchlorate, acetate, propionate, thiocyanate, etc., R1 represents a hydrogen atom or a methyl-group, and Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus especially one of the benzothiazole series,;the benzoselenazole series or the a-naphthothiazole series, with an ester of a dithiocarboxylic acid, especially an ester containing from 3 to 14 carbon atoms, i. e. an ester selected from those represented by the following general formula:

wherein R2 represents a hydrocarbon radical containing from 1 to 6 carbon atoms, e. g. methyl, ethyl, cyclohexyl, phenyl, etc. and R4 represents an alcohol radical containing from 1 to '7 carbon atoms, e. g. methyl, ethyl, n-propyl, n-butyl, benzyl, etc.

Advantageously the condensations are carried out in the presence of a. basic condensing agent. As basic condensing agents, organic tertiary amines are advantageously employed, e. g. trialkylamines (e. g. triethylamine, tri-n-butylamine, triethanolamine, triisoamylami'ne, N- methylpiperidine, N-ethylpiperidine; dimethylaniline, etc). Advantageously the condensa tions are carried out in pyridine containing a'trialkylamine. As esters of dithiocarboxylic acids, methyl dithioacetate, ethyl dithioacetate, methyl dithiopropionate, ethyl dithiopropionate, butyl dithioacet'ate, methyl dithiobenzoate, ethyl dithiobenzoate, benzyl 'dithiobenzoate, methyl dithiocyclohexanecarboxylate, etc. are exemplary. As cyclammonium carboxyalkyl quaternary salts the following are advantageously employed: Z-methylbenzothiazole fl-carboxyethiodide, 2,,4r-dimethylbenzothiazole ,6- carboxyethiodide, 2,5-dimethylbenzothiazole 3- carboxyethiodide, 2,6-dimethylbenzothiazole B- carboxyethiodide, 4 -chloro 2 methylbenzothiazole carboxymethobromide, 5-chloro-2-methylbenzothiazole carboxymethobromide, 6-chloro-2- methylbenzothiazole ,B-carboxyethiodide, 4- methoxy-2-methylbenzothiazole fl-carboxyethochloride, 5-methoxy-2methylbenzothiazole {3- carboxyethiodide, 6-methoxy-2-methylbenzothiazole a-carboxyethobromide, 2-methylbenzoselenazole carboxymethobromide, 5-chloro-2-methylbenzoselenazole B-carboxyethiodide, Z-methyI-anaphthothiazole carboxymethobromide, 2-methyl c-naphthothiazole fl-carboxyethiodide, 2-ethylbenzothiazole p-carboxyethiodide, etc.

The following examples will serve to illustrate further the manner of practicing my invention.

Example 1.-3 8-carbo:ryethyl-2-thiodcetylmeth ylenebenzothiazoline I 021140 0 OH 17.5 g (1 mol.) of 2-methylbenzothiazoleep-carboxyethiodide, 5.3 g. (1 mol.) of methyldithioacetate, 5.0 g. (1 mol.) of triethylamine and 50 cc. of pyridine were boiled together under reflux for 30 minutes. The reaction mixture became red in color and much solid separated out of the boiling solution. The mixture wascooled to room temperature, poured into 600 cc. of 10 per cent-acetic acid and chilled to0 C. with stirring. The solid product was collected on a filter and washed on the filter with water. The crude prodnot was extracted with 300 cc. of hot methyl alcohol. An insoluble residue ofred crystals weighing 5.0 g. was obtained and was identified 3 as detailed below. The alcohol solution was chilled to C., the crystals collected on a filter, washed on the filter with alcohol and dried. The yield of red crystals was 4.4: g., 31 per cent. After recrystallization from absolute ethyl alcohol (160 .uThe insoluble red, crystals obtained inQExample .1, were purified by dissolving in hot methyl alcohol containing an excess of triethylamine beyond that required to form the salt of the dye. The hot. solution was filtered and the dye precipitated from the cooled solution by addition of acetic acid. The dye was obtained as 'dull purple crystals which melted with decomposition at 2189-2 22? C. The yield of purified material was 4.2., g., 3 6 per cent. The dye is a sensitizer from 500to 640 m l with maxima at 540 and 600 m in a gelatino-silver-bromoiodide emulsion. Example 2.-3-,B-carboxyethyl 2- thiopropz'onyl methylenebenzothiazolinc i oemo oon.

' l7.5"gl*(l mol.) 'of- Z-rhethylbenzothiazole B- carboxyethiodi'de; 6.0 g. (1 mol.) of methyldithiopropionate, 5.6g. (l-mol.) of triethylamine and-80 cc. of pyridinewere boiled together under reflux for-30 minutes. The product was separated from aninsoluble Icy-product in the same manner as the preceding example. The yield of bright red crystals was 4.8-g., 33 percent. After recrystallization from absolute ethyl alcohol (30cc. per gram) the product melted withdecomposition at 194-195 C. The .yield of purified; material was 3.0 g., 26 per cent The thioketone is a sensitizer for a gelatino-silver-bromoiodide emulsion to 500 m the insoluble fraction of the crude product consisted of 8.7 g. of purple crystals. This was identified as detailed below.

Example 2a.-Anhydro 3,3" di-B-carboxyethyl- .q-ethylthiacarbocyani'ne hydroxide 7 zHiCQQJ-I The 8.7 g. (72 per cent crude yield) oi purple crystals obtained above. were purified in the same Example 3.-3 fl-cdrb0myethyZ-5-chZ0m-2-thidpropz'onylmethylene-benzothiazoline and anhydro-5,5' dzchloro-3,3'-dz' p carboazyethyl-Slethylthz'acarbocyanine hydroxide 19.2 g. (1 mol.) of 5-chloro-2-methylbenzothiazole p-carboxyethiodide, 6.0 g. (1 mol.) of methyldithiopropionate, 5.0 g. (1 mol.) of triethylamine' and 50 cc. of pyridine were boiled together under The product was isolated in the same manner as Example 1. The yield'of browncrystals was 3.0 g., 18 per cent. After recrystallization from absolute ethyl alcohol (60 cc.

per gram-l the product-melted at 210-212" C; with decomposition. I Theyield of purified material was 2.1 g., 15-per cent. Thethioketone isa sen;

sitizento 500, me in a gelatinoesilver chlorobromoe Y iodide emulsion. A quantityof insoluble red solid was also obtainedfrom the above reaetionmixture. This was dissolvedin 800 cc. of methyl al cohol plus 2 cc. of piperidine, filtered and the dye precipitated by 'the addition of 10 cc. ofgglacial acetic acid. The yieldof brownish crystals was,"

4.1 g., 32 per cent. The dye melted-.at--197 Q. with decomposition. The formula of the dye. is as follows: r J l c ne dtnlcoon den-.000- W Thedyeis a sensitizriromSOO to 660mg with a maximum at 640m ina,gelatino silver bromoiodideilfimulsion. Example 4.3- 3-carb o:cyethg Z-5=chloro-z47110 acetylmethylenebenzothiazoline one thiazol'e p carboxyethiodide; "10.6 g; (.1 mol.)' of methyldi-thioacetate, 10.0" g. (1 moLYoftriethylamine and i00 cc, ofpyridine'wereboiled together 1 under refluxfcr' l5-miliutesl The 'pfoduct awas separated from aquentity of inso'luble purple dye" which occurs-as a Icy-produ t in thesame manner as Example I. 'Ihe-yield of brown crystalswas 8.0 gm, 25-pe1" cent.- Afterrecrystallization-from methy1-alcohol""(100 ccz per gram? the product melted with decomposition at 222 224 c. The

' cirgoo oa 16.1 g '(-1 mol.) of -chloro-2-methylbenzothiaz'ole earboxymethobromide, 6.0 g. (1 mol.) of methyldithiopropionate, 5.0 g. (1 mol.) of triethylamine and 50cc. of pyridine were boiled together-under reflux for 30 minutes. The product was extracted from an insoluble by-product in the same manner as Example 1. The yield of brown crystals was 1.2 g., 8 per cent. After recrystallization from absolute ethyl alcohol (50 cc. per gram) .the product melted with decomposition at 190- 192 C. The yield of purified material was .8 g.,

'5 per cent.-v The thioketone is a. sensitizer to 510 m in a gelatino-silver-chlorobromoiodide emulsion.

Example 5a.Anhydro 3,3 dicarboxymethyl- 5,5-dichloro-9-ethylthiacarbocycmine hydroxide The insoluble product obtained above was purified in the same manner as Example 2a. The purified dye was obtained as dull red crystals which melted at 198'-200 C, with decomposition. The yield of purified material was 2.4 g., 17 per cent. The dye is a sensitizer to 620 m in a gelatino-silver-bromoiodide emulsion.

Example 6. 3-B-carbomyethyZ-Z-thioacetylmethylenebenzoselenaeoline [f ster 19.8 g. (1 mol.) of 2-methylbenzoselenazole-pcarboxyethiodide, 5.3 g. (1 mol.) of methyldithioacetate, 5.0 g. (1 mol.) of triethylamine and 50 cc. of pyridine were boiled together under reflux for 10 minutes. The product was separated from an insoluble by-product in the same manner as Example 1. The yield of brown crystals was 3.8 g., 23 per cent. After recrystallization from absolute ethyl alcohol (50 cc. per gram) the product meltedwith decomposition at 198-200 C. The

yield of purified material was 2.85 g., 17 per cent.

The thioketone is a sensitizer to 610 m with maxima at 520 and 600 m in a gelatino-silver-chlorobromoiodide emulsion.

methylselenacarbocyanin hydroxide emulsion.

19.95 g. (1 mol.) of 2meth yl-u-naphthothiazole B-carboxyethiodide, 5.3 g. (1 mol.) of methyldithioacetate, 5.0 g. (1 mol.) of triethylamine and 50 cc. of pyridine were boiled together under reflux for 10 minutes. The product was separated from an insoluble by-product in the same manner as Example 1. The yield of brown crystals was 2.5 g., 15 per cent; After recrystallization from methyl alcohol cc. per gram) the product melted with decomposition at 200-202 C. The yield of purified product was 1.75 g., 11 per cent. The thioketone is a sensitizer with a maximum at 610 m in a gelatino-silver chlorobromoiodide emulsion.

M O\/\ UN/ I 021140 0 OH The insoluble product obtained above was purified in the same manner as Example 6a. The dye was obtained as dark red crystal-s which 'melted with decomposition at 188l90 Q. The

yield of purified material was 6.2 g., 44 per cent. The dye is a sensitizer from 500 to 650 m with a maximum at 620 m in a gelatino silverbromoiodide emulsion.

The carboxyalkyl quaternary salts employed in practicing my invention are known substances and can be prepared according to United States Patent 2,231,658, dated February 11, 1941, e. g. by reacting theappropriate heterocyclic nitrogen base with halogenated fatty acids. The carboxyalkyl quaternary salts can also be prepared by hydrolysis of the corresponding carbalkoxyalkyl quaternary salts, the preparation of which is also described in the aforesaid United States patent.

The new thioketones obtained in accordance with my invention can be represented by the following general formula:

The thioketones obtained in accordance with my invention can be treated with alkyl salts to yield alkylmercapto compounds represented 'by the following general formula:

wherein R, R2 and Z have the values given above, and R3 represents an alkyl group, e. g.

Example 8.2- (Z-methylmercaptopropenyl) ben- .zothiaeole ,9-carboxyetho-p-tluenesulfonate s CH3 Eta-em.

one os-02C om fooon 1-.-4 (1' mol.) of 3-p-carboxyethyl-2-thioace- 'tylmhylene-benzothiazoline and 0.9 g.

of methyl-p-toluenesulfonate were heated on a steam bath for 30 minutes. A fused mass of 2- (Z-methylmercaptopropenyl) benzothiazole pcarboX'yetho-p-toluenesulfonate was formed.

Example 9.--z-("2-methylmercapto 1 but'enyl) bonzothz'azole p-carbobfyetho-p-toluenesuljonate V 1.45 g. (1 mol.) of 3-,B-carboxyethyl-Z-thiopropionyl-r nethylenebenzothiazoline and 0.9 g. (1 mol.) of me'thyl-p-toluenesulfonate were heated on a'steam bath for one hour. The red solid 2-(2-r nethylmeroapto 1 b'utenyl) benzothiazole B-carboxyetho-p-toluenesulfonate' was Washed by decantation with cc. of diethylet'her.

Example 1U.5-chl0ro-2-(Z-hzethylmgrcapto-I- butenylibeneothiazole p-earbowyetho-ptoluen'eswly oynate 1.1 g. ('1 mol.) of 3 p-carboxyethyl- 5-chloro-2- chloro-2 -thiopropionylmethylenebenzothiazoline and 0.5 g. (1 mol.) of methyl-p toluenesulfonate 'were heated together on the steam bath for minutes. A iusedmass of 5-'chloro-2-(2- methylmercapto-l-butenyl) benzothiazole p carboxyethoedtoluenesulfonate was formed.

Example 1-il .''5-ch'lor'o 2-(2 methylmercaptopropenyh benzothiazole p-ca'rbomyetho-p toluene'sulfonate 1.6 g. (1 mol.) of '3-fl carboxyethyl-5-chloro-2- 'thioacetylmethylenebenzothiazoline and 1.9 g.

me1s.')' of methyl-p teiuenesul'fenate were heated on a steam bath for 90 minutes. A fused mass of 5-chloro-2- (2-methylmercaptopropenyl) ben- 7 zothiazole ,6-carboxyetho-p-toluenesulfonate..

"e. g; the benzenesultenates. the p-toluenes'ultohates, the methylsulfates, the ethylsulfates,

etc. can beeonvert a to the less soluble bromides, iodides or perchlorat'e's by treatment or ahet methyl alcoholic solution of the more soluble 70 quaternary salt with a concentrated aqueous solution of potassium bromide, potassium iodide or sodium perchlorate, chilling the resulting mixture if necessary to precipitate the less soluble alkylmercapto quaternary bromide, iodide or per-- 8. chlorate. Alkylm'ercaipto quaternary chlorides or 'thioc'yanates can be made from thejalkylmere capto quaternary iodides by boiling the-quater nary iodides with a methyl alcoholic suspension 5 of silver. chloride or silver thiocyanate, filtering the silver salts and recovering the alkylmeroapt'o qua-ternary chloride or thiocyanate ,from the methyl alcohol by concentration and chill ing. Ai'kylmercapto quaternary acetates oanbe 10 similarly prepared from quaternary iodides; using silver acetate.

. As shown in the foregoing Examples 1 to; 7..

some of the thiolcetones of my invention and the anhydro meso substituted carbocyanine :hy- 5 droxides of my invention sensitize photographic silver halide emulsions. Sensitization by means of the herein-described thioketones or anhydromeso-substituted carbocyanine hydroxides is primarily directed to the ordinarily employed gelag0 tino-si'lver-halide developing-outemulsions. The

compounds are advantageously incorporated in the washed, finished emulsions and should, of course, be uniformly distributed throughout the emulsions. 1

The concentration of these compounds in the emulsion can vary widely, i. e. from about 5 to about 100 mg. per liter of flowable emulsions. The concentration of the compound will vary according to the type of light-sensitive material in the g emulsion and according to the e'ffe'ct'des'ired; The suitable and most economical concentration for any given emulsion will be apparent to those skilled in the art upon making" the ordinary tests and observations customarily used in the art of 2-5 emulsion making. i

To prepare a gelatino silver-halide emulsion sensitized with one of-these compounds, thefollowing procedure is satisfactory. A quantity of the compound is dissolved in methyl alcohol or 0 other suitable solvent, and a volume of this solution (which may be diluted with water) containing from 5 to 100 mg. of compound is slowly added to about 1,000 'ce. of gelatino silver-ha'lide emulsionwith stirring. Stirring. is continued until the compound is uniformly distributed throughout the emulsion. With most of my new sensitizing compounds, 10 "to 20 mg. of compound per liter {of emulsion to produce'the maximum sensitizing effect with the ordinary gelatino-silverbromiodi'de emulsions.

The above statements are only illustrative and are not to be understoodas limiting my invention, as it will be apparent that these compounds can be incorporated by other methods in any of the photographic silver-halide" emulsions 'eustomari-lyemployed in-the art. For instancathe compounds may be incorporated by bathing a plate or film upon, which an emulsion has been coated in a solution of the compound in-an appropriate solvent.

are not to be preferred ordinarily.

1. A process for simultaneously preparing a thioketone and an anhydro-meso-strbstituted oarbocyanine hydroxide comprising condensing a .cyclammoni-um carboxyal'kyl qua $92117 lected from those represented by thefollowing generaliormula: v

I R-l?'T= C*'O-HrRi wherein R represents a; carboxyalkyl group containing from 2 to 5 carbon atoms, Xrepre nts on r Bathing methods; however,

seam

anion, R1 represents a member selected from the group consisting of a hydrogen atom and a methyl group, and Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the benzothiazole series, those of the benzoselenazole series and those of the oL-naphthothiazole series, with an ester'of a dithiocarboxylic. acid selected from those represented by the following general formula:

wherein R2 represents a hydrocarbon radical containing from 1 to 6 carbon atoms and R4 represents an alkyl group containing from 1 to '7 carbon atoms, in the presence of a basic tertiary organic amine condensing agent, and separating the thioketone from the anhydro-meso-substituted carbocyanine hydroxide.

2. A process for simultaneously preparing a group, and Z represents the non-metallic atoms necessary to complete a heterocyclic nucleusselectedfrom the group consisting of those of the benzothiazole series, those of the benzoselenazole series and those of the m-naphthothiazole series, with an ester of a dithiocarboxylic acid, selected from those represented by the following general formula:

s Rr-B-SIQ wherein R2 represents a hydrocarbon radical containing from 1 to 6 carbon atoms and R4 represents an alkyl group containing from 1 to 7 carbon atoms, in the presence of pyridine and a trialkylamine containing from 6 to 15 carbon atoms, and separating the thioketone from the anhydromeso-substituted carbocyanine hydroxide.

3. A process for simultaneously preparing a thioketone and an anhydro-meso-substituted carbocyanine hydroxide comprising condensing a carboxyalkyl quaternary salt of the benzothiazole series containing a methyl group in the 2-position and containing from 2 to 3 carbon atoms in the carboxyalkyl group, with an ester of a dithiocarboxylic acid selected from those represented by the following general formula:

Bri -SR4 wherein R2 and R4 each represents a saturated hydrocarbon radical containing from 1 to 2 carbon atoms, in the presence of pyridine and a trialkylamine containing from 6 to 15 carbon atoms and separating the thioketone from the anhydromeso substituted carbocyanine hydroxide.

4. A process for simultaneously preparing a thioketone and an anhydro-meso-substituted carbocyanine hydroxide comprising condensing a carboxyalkyl quaternary salt of the benzoselenazole series containing a methyl group in the 2- position and containing from 2 to 3 carbon atoms 10 in, the carboxyalkyl group, with an ester of a die thiocarboxylic acid selected from those represented by the following general formula:

R2 I l-SR4 wherein R2 and R4 each represents a saturated hydrocarbon radical containing from 1 to 2 carbon atoms, in the presence of pyridine and a trialkylamine containing from 6 to 15 carbon atoms and separating the thioketone from the anhydromeso-substitut'ed carbocyanine hydroxide. g

5. A process forsimultaneously preparing a thioketone' and an anhydro-meso-substituted carbocyanine hydroxide comprising condensing a carboxyalkyl quaternary salt of the wnaphthothiazole series-containing a methyl group in the-2- position and containing from 2 to 3' carbon atoms in the carboxyalkyl group, with an ester of a dithiocarboxylic acid selected from those represented by the following general formula:

wherein R2 and R4 each represents a saturated.

hydrocarbon radical containing from 1 to 2 car bon atoms, in the presence of pyridine and a trialkylamine containing from 6 to 15 carbon atoms and separating the thioketone" from the anhy- 1 dro-meso-substituted carbocyanine hydroxide.

, 6. A compound selected from the group of compounds which are represented by the following general formulas:

wherein R represents a carboxyalkyl group containing from 2 to 5 carbon atoms, R1 represents a member selected from the group consisting of a hydrogen atom and a methyl group, R2 represents a hydrocarbon radical containing from 1 to '6 carbon atoms, X represents an anion, R3 represents an alkyl group containing from 1 to 7 carbon atoms and Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the benzothiazole series, those of the benzoselenazole series and those of the a-naphthothi azole series.

7. A compound selected from the group of compounds represented by the following general formulas:

V 11 pouridsrepre'sented by emanat ng general formules: p

and-

Ii -N V s H=J SR,

wherein R represents a carboiyalkyigroup containing from 2 t0 3 carbons atoms, R2 and R3 each represents a primary alkyl group of the formula CmHzm+1 wherein m represents a positive integer of from 1 to 4, X represents an anion and. Z represents the nonmetallic atoms necessary to complete a heterocyclic nucleus of the benzoselenazole sev ries.

10. The thioketone which is represented by the following formula: v

\ I on;

' (EH40 OOH 11. The thioketone which following formula 1' /Se CH 7 3 \V I o=oH- os 12; The 'thioketone which is represented by the following formulaz. v v c v s I *om. oion is I,

C2H4CCOH ROBERT H. SPRAGUE.

REFERENCES em The following references are ofrecor din'th file of this patent: V V s r UNITED, s'rATEs PATENTS Number Name I 2,231,658 Brookeret a]; Febrll", 1941 2,315,498 'Brooker et al. Apr. 6,. 19513 2,332,517 "Kendall 'Oct. 26,1943 2,354,524 Kumetat et a1 -Ju1y 25, 1944 2,369,646

is represented by the":

' Brooker et al. Feb; 20, 1945 

